This invention concerns hand tools for applying hot melt adhesive and the like to work surfaces.
Many such presently available hand tools, or hand guns as they are generally called, are supplied with adhesive in the form of solid cartridges or slightly flexible ribbon. U.S. Pat. No. 3,443,059, issued on May 6, 1969 to Robert A. Spencer and assigned to the assignee of the present application, is illustrative of such hand guns. Although useful for many purposes, such guns are not satisfactory for heavy work which requires the melting and application of large amounts of material.
For such relatively heavy work is is more satisfactory to employ a conventional source of pressurized molten adhesive or the like, which is supplied to the hand gun through a flexible hose. However, previously available hand guns operating on that principle are subject to serious disadvantages.
The flexible conduit or hose through which adhesive is supplied to the gun tends to be stiff and heavy, complicating accurate manipulation of the gun. That is especially true if the hose approaches the gun horizontally, since the operator's hand must then support an appreciable length of hose in addition to the gun itself.
In some hand guns for applying hot melt adhesive and the like the molten adhesive is supplied from below, entering the gun through the handle by which the operator grasps and manipulates the tool. U.S. Pat. No. 3,543,968 is illustrative of that configuration. However, despite the rather elaborate precautions described in that patent, it is difficult or impossible to reconcile the need to maintain the entering adhesive in molten condition and the need to protect the operator's hand from uncomfortable or harmful heat.